合并两个相同的作业

db/migrate/20160511055221_merge_two_homeworks.rb

@@ -0,0 +1,20 @@
+class MergeTwoHomeworks < ActiveRecord::Migration
+  def up
+    student_works = StudentWork.where("homework_common_id = 3387 and user_id in (11256, 11259, 11252, 11499)")
+    unless student_works.nil?
+      student_works.each do |work|
+        work.update_column('homework_common_id', 3463)
+      end
+    end
+    homework = HomeworkCommon.find 3387
+    homework.destroy if homework
+    stu_works = StudentWork.where("homework_common_id = 3387")
+    stu_work_ids = stu_works.empty? ? "(-1)" : "(" + stu_works.map{|work| work.id}.join(',') + ")"
+    stu_work_tests = StudentWorkTest.where("student_work_id in #{stu_work_ids}")
+    stu_work_tests.destroy_all if stu_work_tests
+    stu_works.destroy_all if stu_works
+  end
+
+  def down
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20160509025404) do
+ActiveRecord::Schema.define(:version => 20160511055221) do
 
   create_table "activities", :force => true do |t|
     t.integer  "act_id",                                  :null => false
@@ -1107,23 +1107,6 @@ ActiveRecord::Schema.define(:version => 20160509025404) do
     t.integer  "viewed_count",  :default => 0
   end
 
-  create_table "mess", :id => false, :force => true do |t|
-    t.string   "课程名"
-    t.integer  "课程ID",                    :default => 0,  :null => false
-    t.string   "教师姓",                     :default => "", :null => false
-    t.string   "教师名",       :limit => 30, :default => "", :null => false
-    t.string   "主贴名",                     :default => "", :null => false
-    t.integer  "主贴或回帖ID",                 :default => 0,  :null => false
-    t.integer  "回帖对应主贴ID"
-    t.integer  "帖子点赞数"
-    t.integer  "主贴回复数",                   :default => 0,  :null => false
-    t.text     "主贴或回帖内容"
-    t.datetime "发帖时间",                                    :null => false
-    t.integer  "发帖或回帖用户ID",               :default => 0,  :null => false
-    t.string   "发帖或回帖用户姓",                :default => "", :null => false
-    t.string   "发帖或回帖用户名",  :limit => 30, :default => "", :null => false
-  end
-
   create_table "message_alls", :force => true do |t|
     t.integer  "user_id"
     t.integer  "message_id"